BOSTON — Republican former FDIC chairwoman Sheila Bair endorsed Democratic Senate candidate Elizabeth Warren on Wednesday, saying it is the first time she has endorsed a Democrat.

Bair campaigned with state treasurer Steve Grossman, who has been acting as a surrogate for Warren, at the Boston Firefighters Credit Union in Dorchester, and planned to travel with Warren to Worcester and Lowell.

Bair said she first met Warren when she asked Warren to serve on an advisory committee on economic inclusion at the FDIC, which focused on expanding access to banking services for underserved populations. They also worked together when Warren chaired a congressional oversight panel that oversaw the use of federal bailout money, and when Warren advised Democratic President Barack Obama on setting up the Consumer Financial Protection Bureau, an agency created by the Dodd-Frank financial reform bill to look out for consumer interests. Warren said when she was working on creating the bureau, Bair was the only Washington regulator to support it. Time Magazine labeled both women “sheriffs of Wall Street,” along with Securities and Exchange Commission chairwoman Mary Schapiro.

“She’s whip-smart, she’s effective, she’s articulate, she cares about people and she is a good manager too,” Bair said.

Warren praised Bair’s work helping families avoid foreclosure during the 2008 financial crisis and generally looking out for consumers.

Bair said she would not say anything negative about Warren’s opponent, Republican U.S. Sen. Scott Brown. She has been supporting Republican female senatorial candidates this election cycle, including Linda McMahon of Connecticut, Deb Fischer of Nebraska and Heather Wilson of New Mexico. Bair has not endorsed in the presidential race.

Massachusetts Democratic U.S. Rep. Barney Frank, the former chairman of the House Financial Services Committee who endorsed Warren, said in a statement, “I am not surprised that Sheila Bair – a genuine practitioner of real, principled bipartisanship – has crossed party lines to endorse Elizabeth Warren for the Senate. These two women are among those with whom I was proud to work most closely in putting together a tough financial reform bill, and Sheila Bair’s support for Elizabeth Warren is wholly consistent with her record of fighting for tough, fair rules for the financial industry that protect the economy, consumers and investors.” The Dodd-Frank financial reform bill was named for Frank and U.S. Senate Banking Committee Chairman Chris Dodd.

Bair is a former professor of financial regulatory policy at the Isenberg School of Management at the University of Massachusetts at Amherst, where she worked from 2002 to 2006. She was appointed chairwoman of the FDIC by Republican President George W. Bush in 2006 and served through 2011. After leaving that position, she joined The Pew Charitable Trusts as a senior adviser.

She is credited for her early warnings about the housing bubble. In 2008, there was speculation that she was being considered for the position of Treasury Secretary under Obama – a job that ultimately went to Timothy Geithner. Her involvement in Republican politics dates back at least to the 1980s, when Bair worked as research director and counsel to former Senate Majority Leader Bob Dole.

Bair wrote a book, “Bull by the Horns,” in which she criticized the Bush and Obama administrations for rescuing the banks but not doing enough to help homeowners facing foreclosure. “The policies were all focused on making banks profitable again,” Bair told the Washington Post.

Warren publicly grilled Geithner when she was chairing the Congressional oversight panel, and has said in the past that she has disagreed with Obama on the administration’s handling of the mortgage foreclosure crisis. “To this day, I think the actions have been too small, too slow and not provided the kind of permanent solutions we need,” Warren told reporters in August.

On Wednesday, asked about Bair’s critique of Obama’s policies, Warren said she was outspoken herself while on the Congressional oversight panel. “I was willing to hold everyone accountable, the Bush administration, the Obama administration, the large financial institutions,” Warren said. “For me it was about speaking out on behalf of the public.”

Brown has made bipartisanship a hallmark of his campaign, and has rolled out numerous endorsements from local and state Democratic politicians. Bair, the first prominent Republican to back Warren, said she believes Warren will be “independent of industry” and will assimilate all different viewpoints and cross party lines to come up with proposals that serve the public.